Mass air flow meter

• US 4,750,352 A
• Filed: 08/12/1987
• Issued: 06/14/1988
• Est. Priority Date: 08/12/1987
• Status: Expired due to Term

• Current Assignee: General Motors Auto OOO (General Motors Company)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Kolhoff, James B.
• Primary Examiner(s): Dolinar, Andrew M.
• Application Number:
  US07/084,573
• Time in Patent Office: 307 Days
• Field of Search: 123/480, 123/486, 123/494, 73/117.3, 73/118.2, 364/431.04, 364/431.05
• US Class Current: 73/114.33
• CPC Class Codes: F02D 41/182 for the control of a fuel injection device
• CPC Class Codes: F02D 41/32 of the low pressure type F02D41/3082 takes precedence
• CPC Class Codes: G01F 1/34 by measuring pressure or differential pressure
• CPC Class Codes: G01F 1/88 with differential-pressure measurement to determine the volume flow

Abstract

A system and method for measuring the air flow into an engine including a throttle bore and a throttle for varying the effective area of the throttle bore and a throttle bypass passage including a bypass valve for varying the effective area of the bypass passage. The air meter determines the air flow into the engine based upon the effective area established by the throttle and the bypass valve and where at closed throttle position the effective area of the throttle at closed position is determined based upon the air flow into the engine through the bypass passage when the engine idle speed is controlled to a predetermined idle speed.

Claims

1. A closed throttle air flow meter for an internal combustion engine having an intake manifold, an induction passage opening from the atmosphere to the intake manifold and including a throttle bore and a variable position throttle in the throttle bore for varying the effective area of the induction passage to regulate the air flow into the intake manifold and further including a throttle bypass passage opening from the atmosphere to the intake manifold and including a variable position valve for varying the effective area of the bypass passage to regulate the air flow into the intake manifold bypassing the throttle, the air flow meter comprising, in combination:

means for controlling the position of the valve in the bypass passage to control the engine idle speed to a predetermined value during an idle speed operating mode of the engine, the total air flow into the intake manifold at the desired engine idle speed having a predetermined value so that the air flow through the throttle bore is equal to the predetermined value less the air flow through the bypass passage;

means for storing the position of the variable position valve when the engine is at the predetermined idle speed value during the engine idle speed operating mode, the stored value representing the air flow value through the bypass passage and therefore the flow value and effective area of the induction passage opening defined by the closed throttle;

means for storing a schedule of values of the effective area A₁ of the induction passage opening defined by the closed throttle as a function of the position of the variable position valve when the engine is at the predetermined idle speed;

means for storing a schedule of values of the effective area A₂ of the bypass passage defined by the position of the variable position valve;

means for measuring the value P₀ of the barometric pressure;

means for measuring the value P₁ of the intake manifold;

means for measuring the value T of the manifold air temperature;

means responsive to the scheduled values of A₁ and A₂ corresponding to the stored position of the variable position valve and the present value of the variable position valve, respectively, and the values P₀ of the barometric pressure, P₁ of the intake manifold and T of the manifold air temperature for determining the total air flow into the engine during closed throttle position in accord with the expression AIR FLOW =(A₁ +A₂) F(P₀) F(P₁ /P₀) F(T) where F(P₀), F(P₁ /P₀) and F(T) are predetermined functions of the pressure P_O, the pressure ratio P₁ /P₀ and the temperature T.